Australia is home to 223 species of marsupial.
Lacking a womb our mammalian cousins give birth to their young at a very early stage of development and then nurse them to maturity. Female marsupials also have 3 vaginas but that is another thread.
The earliest fossils of marsupials are not to be found in Australia however but in North America 80 million years ago. Their journey can be followed south all the way to the tip of South America 40 million years ago and then they suddenly turn up in Australia 30 million years ago.
So where were Joey's ancestors during the missing 10 million years and how did they manage to get to Australia?
In a word the answer is Gondwana.
Throughout the earth's history the continents have been constantly in motion, crashing together to form supercontinents and ripping apart again in various formations. The world we see today is a snapshot in geological time.
During the Late Cretaceous Period South America and Australia were joined to either end of Antarctica to form what was left of Gondwana which began to unzip in the Triassic.
This leads to a testable prediction. If evolution is true then it ought to be possible to find fossils of marsupials with the correct antiquity in Antarctica.
In his book ''Cold,'' published in 1931 Dr. Lawrence M.Gould wrote ''I had rather go back to the Antarctic and find a fossil marsupial than three gold mines.''
In 1982 an expedition funded by the National Science Foundation found fossils of more than a dozen species of marsupial on Seymour Island right on the ice-free corridor between South America and Antarctica. The fossils were dated to between 35 and 40 million years ago and were similar to those found in South America at the same time.
Just like Tiktaalik the marsupial story is an example of how the fact of evolution can be tested in the real world and shown to be accurate.
In an alternative hypothesis all 223 species of marsupial walked and swam in pairs from Mount Ararat to Australia via Antarctica. The evidence for this explanation is a bit more tenuous however.
|Part 1 - Protein Functional Redundancy - - - - - - - -||Part 2 - DNA Functional Redundancy|
|Part 3 - ERVs||Part 4 - Smelly Genes|
|Part 5 - Vitamin C||Part 6 - Human Chromosome 2|
|Part 7 - Human Egg Yolk Gene||Part 8 - Jumping Genes|
|Part 9 - Less Chewing More Thinking||Part 10 - Non-Coding DNA|
|Part 11 - Tiktaalik||Part 12 - Lenski's E.coli Experiment|
|Part 13 - Morris Minor Bonnets|